Default action of AddContainer will now be append

src/Editor.tsx

@@ -212,13 +212,19 @@ class Editor extends React.Component<IEditorProps> {
       throw new Error('[OnPropertyChange] Container model was not found among children of the main container!');
     }
 
+    let x = 0;
+    const lastChild: IContainerModel | undefined = parent.children.at(-1);
+    if (lastChild !== undefined) {
+      x = lastChild.properties.x + Number(lastChild.properties.width);
+    }
+
     // Create the container
     const newContainer = new ContainerModel(
       parent,
       {
         id: `${type}-${count}`,
         parentId: parent.properties.id,
-        x: 0,
+        x,
         y: 0,
         width: properties?.Width,
         height: parent.properties.height,